The "Fire Weather Hazard Map" depicts the local threat (weather-related only) of potential wild fires for specified areas. It is largely based on the character of surface relative humidity (the effects on fuel moisture), 20-foot wind speed (the effects on wild fire growth, spread, and spotting), and lightning (a natural ignition source).
Fire Weather
Threat Level |
Threat Level Descriptions |
Extreme |
"An Extreme Threat to Life and Property from Existing or Potential Wildfires Due to Weather."
- Wildfire weather conditions meet Red Flag criteria with KBDI ≥ 600 and with winds ≥ 15 mph (or wind gusts ≥ 15 mph from nearby lightning storms).
|
High |
"A High Threat to Life and Property from Existing or Potential Wildfires Due to Weather."
- Wildfire weather conditions meet Red Flag criteria with KBDI ≥ 600 and with winds < 15 mph.
- OR... Wildfire weather conditions meet Red Flag criteria with KBDI 400 - 599 and with winds ≥ 15 mph (or wind gusts ≥ 15 mph from nearby lightning storms)
|
Moderate |
"A Moderate Threat to Life and Property from Existing or Potential Wildfires Due to Weather."
- Wildfire weather conditions approaching Red Flag criteria with KBDI ≥ 600.
- OR... Wildfire weather conditions meet Red Flag criteria with KBDI 400 - 599 and with winds < 15 mph.
- OR... Wildfire weather conditions meet Red Flag criteria with KBDI 200 - 399 and with winds ≥ 15 mph (or wind gusts ≥ 15 mph from nearby lightning storms).
|
Low |
"A Low Threat to Life and Property from Existing or Potential Wildfires Due to Weather."
- Wildfire weather conditions below Red Flag criteria with KBDI ≥ 600 with significant existing wildfire(s)
- OR... Wildfire weather conditions approaching Red Flag criteria with KBDI 400 - 599.
- OR... Wildfire weather conditions meet Red Flag criteria with KBDI 200 - 399 and with winds < 15 mph.
- OR... Wildfire weather conditions meet Red Flag criteria with KBDI < 200 and with winds ≥ 15 mph (or wind gusts ≥ 15 mph from nearby lightning storms).
|
Very Low |
" A Very Low Threat to Life and Property from Existing or Potential Wildfires Due to Weather."
- Wildfire weather conditions below Red Flag criteria with KBDI 400 - 599 and significant existing wildfire(s).
- OR...Wildfire weather conditions approaching Red Flag criteria with KBDI 200 - 399.
- OR...Wildfire weather conditions meet Red Flag criteria with KBDI < 200 and with winds < 15 mph.
|
Non-Threatening |
" No Discernable Threat to Life and Property from Existing or Potential Wildfires Due to Weather."
- Wildfire weather conditions are below Red Flag criteria and non-threatening.
|
Red Flag Conditions - In Florida, Red Flag conditions occur in a given area when the relative humidity is 35 percent or less for a period of 4 hours or more... OR ...when the relative humidity is 35 percent or less for a period of 1 to 3 hours in the presence of winds of 15 mph or more... OR ...when the relative humidity is 35 percent or less in the presence of dispersion indices of 75 or more.
Keetch-Byram Drought Index (KBDI) - The Keetch-Byram Drought Index (KBDI) is a system for relating recent weather conditions to expected fire potential and behavior. It consists of drought index values ranging from 0 to 800 that describe moisture availability within wildfire fuels and soil. A rating of zero defines the wettest cnditions possible (very wet) and 800 defines the maximum drought conditions possible (very dry). |
National Weather Service Forecast Office
